Introduction to Luminescent Materials
Luminescent materials refer to materials that can absorb energy and convert it into light radiation (non-equilibrium radiation). The phenomenon of luminescence is widely present in various materials, so there are many types of luminescent materials. Driven by modern technology, luminescent materials are increasingly becoming key elements in many industries. From lighting to display technology to medical applications, the potential of these materials is being continuously explored.
Types of Luminescent Materials
The types of luminescent materials can be classified according to their luminescence mode and composition. According to the luminescence mode, luminescent materials can be divided into the following types:
Photoluminescence: This material emits light by absorbing photons or light excitation. Common excitation light sources include ultraviolet light.
Electroluminescence: This material emits light by applying an electric field to it. It is commonly used in display technologies such as LEDs.
Iridium Complexes: Iridium complex is a phosphorescent material whose luminescence process involves an electronic transition from an excited state to a ground state. Under the action of the heavy metal atom in the iridium center, the spin-orbit coupling effect is significantly enhanced, allowing the triplet transition of the singlet excited state to occur, thereby improving the luminous efficiency of the material. Compared with traditional organic fluorescent materials, iridium complexes have high luminous efficiency, long luminous lifetime, and high stability at room temperature.
Thermoluminescence: When a material is heated, it releases previously absorbed energy and emits light.
Radioluminescence: It emits light through radiation excitation from radioactive particles.
Chemiluminescence: Light emission produced by the release of energy from chemical reactions, such as the reaction of Luminol with oxidants to produce blue light.
Bioluminescence: The phenomenon of organisms producing light through chemical reactions. It is common in deep-sea organisms.
Mechanical luminescence: Light emission is triggered by mechanical energy such as pulling or tearing.
In addition, according to the composition of the material, luminescent materials can also be divided into two categories: organic and inorganic:
These classification methods reflect the diversity of different types of luminescent materials in structure, composition and application fields.
Application Fields of Luminescent Materials
Display technology
Luminescent materials occupy a core position in display technology. Taking organic light-emitting diodes (OLEDs) as an example, organic luminescent materials are used in OLED displays because of their adjustable color and brightness, and are superior to traditional liquid crystal displays (LCDs) in color expression. Literature shows that the light efficiency and color purity of OLED materials have reached more than 90%, and their plasticity and low power consumption characteristics have led to their widespread use in high-end display devices.
In addition, the application of quantum dot technology has greatly improved the color performance of displays. Quantum dot materials, with their narrow spectrum emission and wide absorption spectrum, enable displays to achieve higher color saturation. According to research data, quantum dot materials can enable displays to achieve a color gamut coverage of more than 95%, which means that a wider range of natural colors can be reproduced, making it an important choice for high-resolution televisions and computer monitors.
Medical imaging and diagnosis
Luminescent materials have unique advantages in the field of medical imaging and diagnosis, especially fluorescent dyes and quantum dots play a vital role in biomarkers and imaging applications. Fluorescent dyes such as FITC and rhodamine can be used as markers for cells, DNA, and proteins, which helps to observe cell activities. Related studies have shown that the signal intensity of FITC-labeled proteins can last for more than 96 hours, and it still has high sensitivity under low concentration conditions, which is suitable for long-term dynamic observation.
The application of quantum dots in biological imaging shows higher stability and color diversity, and can achieve multi-channel imaging, so that one imaging system can detect multiple biological targets. According to experimental data, quantum dot labeling technology has a detection sensitivity that is about 20 times higher than that of traditional dyes, so it can be used for early cancer detection, infection diagnosis and disease labeling.
Lighting technology
Luminescent materials are also widely used in lighting technology, especially inorganic luminescent materials such as aluminum gallium nitride (AlGaN) and gallium phosphide (GaP), which are used to manufacture high-efficiency LED light sources. The high brightness and long life of LED materials make them ideal for home lighting, car headlights, signal lights, etc. Research data show that the luminous efficiency of AlGaN-based LED materials reaches about 150 lm/W, which is more than 10 times higher than that of traditional incandescent lamps, and its service life can reach more than 50,000 hours.
In addition, the emerging blue LED light source combined with yellow phosphor achieves white light emission. By improving the light conversion efficiency of the phosphor, it can achieve higher brightness under extremely low energy consumption conditions, making luminescent materials the key to energy-saving lighting.
Solar energy technology
In the field of solar energy technology, luminescent materials are used to improve the efficiency of photoelectric conversion. In particular, upconversion luminescent materials and downconversion materials help absorb more solar spectrum and improve the efficiency of solar cells by converting invisible light into visible light. According to research, the use of upconversion materials (such as europium and erbium-doped inorganic crystals) can increase the photoelectric efficiency of solar cells by about 10%-15%, thereby significantly enhancing the utilization of solar energy.
